Motorcycles typically include a frame and a swingarm pivotally connected to the rear of the frame (e.g., either directly or through the engine). The swingarm supports the rear axle and rear wheel of the motorcycle. The rear axle typically extends through the swingarm, and is secured in place by an axle nut. The positioning of the axle relative to the swingarm can be changed by use of an axle adjuster. More specifically, the axle nut can be loosened and the adjuster can be used to move the rear axle relative to the swingarm to change the tension in the flexible drive member (e.g., a chain or belt).
For functional and aesthetic reasons, portions of the rear axle or adjuster are sometimes covered. For example, rear axles and corresponding axle nuts can be covered with an axle end cap or cover. Rear axle covers are functional and aesthetically pleasing additions to motorcycles. Similarly, axle adjusters can be covered with an adjuster end cap to enhance the function and aesthetics of the adjuster. Such covers and end caps are commonly brightly polished and/or have ornamental designs or logos. These covers and end caps may also reduce the amount of contaminants that reach and corrode these components.